Nanosized inorganic metal oxides as heterogeneous catalysts for the degradation of chemical warfare agents

Nanosized inorganic metal oxides, such as TiO₂, ZnO, γ-Al₂O₃, are proposed as heterogeneous catalysts for the oxidative degradation of chemical warfare agents (CWA), particularly of organosulfur toxic agents, into oxidised products with reduced toxicity. The morphology, structural and textural properties of the catalysts were investigated. Furthermore, their catalytic properties were evaluated in the oxidative abatement of (2-chloroethyl)ethylsulfide, CEES, a simulant of sulfur mustard (blistering CWA). Their performance was also compared to a conventional decontamination powder and a commercial Nb₂O₅ sample. The metal oxides powders were then employed in the active oxidative decontamination of CEES from a cotton textile substrate, mimicking a real contamination occurrence. Remarkable results in terms of abatement and degradation into desired products were recorded, achieving good conversions and decontamination efficiency with Nb₂O₅, TiO₂ and γ-Al₂O₃, under very mild conditions, with hydrogen peroxide (as aqueous solution or as urea-hydrogen peroxide adduct), at room temperature and ambient pressure. In the aim of a real on-field use, the potential environmental impact of these solids was also evaluated by bioluminescence toxicity tests on reference bacteria (Photobacterium leiognathi Sh1), showing a negligible negative impact for TiO₂, γ-Al₂O₃, and Nb₂O₅. A major biotoxic effect was only found for ZnO.